1. Field of the Invention
The present invention relates to a large-sized recording system employing a recording module having a recording head in plural units.
The present invention also relates to a recording apparatus, a conveying apparatus and a recording system in which a recording operation is achieved by sharing among plural recording units.
2. Related Background Art
In a prior recording system for printing a recording medium of a relatively large size with a line head, in case the ink discharge is not executed for a certain period in a part of plural ink discharge nozzles in the recording head, such nozzles may be dried to induce a viscosity increase in the ink, whereby a proper recording performance may not be maintained.
In order to maintain the recording performance and the continuity in the recording operation, there is proposed a recording apparatus which, utilizing an interval of recording sheets after the lapse of a predetermined time, executes a forced ink discharge in a holed part of a conveying belt before a next recording sheet is supplied (for example cf. Japanese Patent Application Laid-open No. 2001-113690).
Also utilizing the recent remarkable progress in the recording resolution with a sufficiently small ink amount in a single discharge, there is proposed a method of dispersing preliminary discharges, separate from discharges for image data, in a marginal area so as to be visually unnoticeable thereby maintaining the proper discharge performance of the nozzles (for example cf. Japanese Patent Application Laid-open No. 2004-25627).
On the other hand, in case the ink discharges are concentrated as a burst or in case a cumulative number of pixel recordings on a same nozzle exceeds a certain number, an ink drop may be formed in the vicinity of such nozzle whereby a proper recording performance may not be maintained locally.
Therefore, in order to maintain a proper recording performance, the recording operation is interrupted after the ink discharge of a predetermined amount in a certain nozzle area and a wiping (cleaning) operation by a wiper blade or the like for wiping off the ink in the vicinity of the nozzle is inserted.
In order to reduce the time of interruption by such cleaning operation, there is proposed a structure of providing plural recording heads, and, during the cleaning operation for a recording head in the course of a recording operation, switching the recording operation to the other recording head (for example cf. Japanese Patent Application Laid-open No. 7-76093).
As to the preliminary discharge for refreshing the nozzles at every predetermined time, it can now be suppressed to a visually unnoticeable level by dispersing the discharges according to the method of Japanese Patent Application Laid-open No. 2004-25627 mentioned above. However, in the wiping (cleaning) operation by a wiper blade or the like for wiping off the ink in the vicinity of the nozzle, the recording operation of the head has to be temporarily interrupted according to the methods described in Japanese Patent Application Laid-open Nos. 2001-113690 and 2004-25627.
Also the method described in Japanese Patent Application Laid-open No. 7-76093 may significantly reduce the time of interruption during the cleaning operation, while, with respect to the continuousness of recording operation and continuity of the recording, it is effective for images sectioned by each recording medium or each page, but a slight interruption in the recording operation occurs by the switching of the recording heads in case of a high-speed recording on a continuous sheet with a small label interval as in the case of a label printer, and, in case the image changes continuously as in cloth pattern printing, a wallpaper printing or a form printing, a cumbersome sheet returning operation is required even for such slight interruption in order to secure continuity in the image recorded after the interruption.
Also in the performance of the recording apparatus, despite of the presence of plural recording heads, a maximum possible recording speed cannot be attained. In other words, it is limited to a recording speed always in consideration of a speed decrease resulting from the interruption of recording in the heat to be cleaned.
Also in a recording apparatus for a high-speed image formation on a relatively wide recording sheet with plural recording heads or plural recording head modules, there is known a configuration of positioning carriages, supporting such recording head modules, to the respective recording positions by independent guide shafts (for example Japanese Patent Application Laid-open No. 2003-127352).
Also recently known is a wide-format recording apparatus in which the recording area is shared among plural recording apparatuses arranged in a staggered fashion along the transversal direction of the recording sheet (for example PCT/JP2004/007912).
However, in the configuration described in Japanese Patent Application Laid-open No. 2003-127352, requiring a carriage and a carriage sliding unit independent for each recording module, the space of the entire mechanism in the sheet conveying direction increases substantially proportionally to the recording width. Also in order to continue the recording operation during the cleaning operation of the recording head in the course of the recording operation, at least two recording modules have to be provided, so that the space in the sheet conveying direction is at least doubled.
Also the configuration described in PCT/JP2004/007912 involves an interruption in time during the cleaning operation. Also the recording apparatus for each recording area functions independently, a displacement in the recording position inevitably occurs at each up-down motion of the recording head. Consequently the continuity of image is slightly perturbed at the boundary of the areas of the recording apparatuses, and, in order to avoid such perturbation, the image to be recorded has to be prepared under certain restriction.